Such a method with use of semiconductor switching elements is known from WO 2001/022447. The method described there operates not only with electrical switching means, i.e. insulated gate bipolar transistors known as IGBTs, but also mechanical contacts. It is designed so that the actual load changeover takes place at the zero transition of the load current by two IGBTs with diodes in rectifier-circuit arrangement. A necessary component of this known method is the recognition and detection of the respective current zero transition as a precondition for initiating the load changeover at this instant.
A further method with an IGBT switching arrangement, in which the taps of the regulating winding of a power transformer are connected by a series connection of two IGBTs with a common load shunt, is known from WO 1997/005536 [U.S. Pat. No. 5,969,511]. This known method operates according to the principle of pulse width modulation; in a further method step, limitation of the current is in that case carried out by the transient reactive reactance (TER) of the tapped winding. This method requires a specific adaptation of the on-load tap changer to the respective tapped transformer to be connected. In other words, the tapped transformer and the on-load tap changer have to be matched to one another and interact electrically. This known method is therefore not suitable for use in a separate, universally usable on-load tap changer not tailor-made for a specific transformer.